Biotechnology and Bioengineering, Vol.117, No.9, 2715-2727, 2020
Scalable, two-stage, autoinduction of recombinant protein expression in E. coli utilizing phosphate depletion
We report the scalable production of recombinant proteins in Escherichia coli, reliant on tightly controlled autoinduction, triggered by phosphate depletion in the stationary phase. The method, reliant on engineered strains and plasmids, enables improved protein expression across scales. Expression levels using this approach have reached as high as 55% of the total cellular protein. The initial use of the method in instrumented fed-batch fermentations enables cell densities of similar to 30 gCDW/L and protein titers up to 8.1 +/- 0.7 g/L (similar to 270 mg/gCDW). The process has also been adapted to an optimized autoinduction media, enabling routine batch production at culture volumes of 20 mu l (384-well plates), 100 mu l (96-well plates), 20 ml, and 100 ml. In batch cultures, cell densities routinely reach similar to 5-7 gCDW/L, offering protein titers above 2 g/L. The methodology has been validated with a set of diverse heterologous proteins and is of general use for the facile optimization of routine protein expression from high throughput screens to fed-batch fermentation.